Wandering is a severe risk factor for persons with dementia and other psychiatric disorders. It is estimated that over six million Americans have dementia and wandering may occur in as many as sixty percent of dementia patients during their disorder. Wandering by a person with dementia or other psychiatric disorders can be dangerous and can lead to injury or even death due to falls, accident and/or exposure.
There are a number of anti-wandering technologies available to prevent wandering: pressure activated alarms, which sound when a pad, mat, or pillow is depressed as a subject attempts to leave a confined area; pull tab alarms, which sound when a tab is removed from the device; audible door alarms, which activate when a monitored door is accessed; optically-activated alarms, which activate when motion is detected; and visual deterrents, which are visual obstacles used to prevent access to forbidden areas.
These technologies provide the ability to track and locate a wandering subject. However, these tracking systems have a number of drawbacks. First, they rely primarily on alarms, which can lead to agitation in a wandering subject. Additionally, alarms have little or no use to a caregiver or wandering subject whose hearing is poor. Second, the tracking systems are subject to accidental triggering. For instance, a house pet may set them off and many of the tracking systems do not have sensitivity adjustments. Third, tracking systems may fail to give accurate vector information for proper tracking of the wandering subject.
Dementia and wandering behavior are independent predictors of falls of nursing home residents. While gait and balance disturbances have been precisely quantified using devices such as gait mats and accelerometers (J. L. Fozard, Sensory and Cognitive Changes With Age, in M. P. K. W. Schaie, Ed., Mobility and transportation in the elderly, New York: Springer, pp. 1-44 (2000); W. J. Evans, Effects of Exercise on Body Composition and Functional Capacity of the Elderly, in M. P. K. W. Schaie, Ed., Mobility and transportation in the elderly, New York: Springer, pp. 71-90 (2000); G. Allah, R. W. Kressig, F. Assal, F. R. Herrmann, V. Dubost, & O. Beauchet, Changes in gait while backward counting in demented older adults with frontal lobe dysfunction, Gait & Posture, 26(4), pp. 572-576 (2007); J. Verghese, J., R. B. Lipton, C. B. Hall, G. Kuslansky, M. J. Katz, & H. Buschke, Abnormality of gait as a predictor of non-Alzheimer's dementia, New England Journal of Medicine, 347(22), pp. 1761-1768 (2002)), detecting and quantifying wandering behavior within everyday movements has remained a challenging task because it occurs over large areas. Wandering is defined as repetitive or random variations in unconstrained voluntary movements. Wandering can manifest during goal-directed movements, e.g., traversing the bedroom to the bathroom, and in aimless movements. A key feature of wandering is path variability across an open field, a dimension not usually measured in laboratory-based studies of gait, which have traditionally focused on gait consistency in a prescribed course.
Past attempts to measure wandering have limitations. Using well-trained human observers, a behavioral rating scale has been developed allowing classification of different wandering patterns in open field situations. While successful, applications of this technology are usually obtrusive, require vigilant observers, and necessarily restrict the range in which observations are feasible. Algase and colleagues have compared the effectiveness of four accelerometer-based devices to detect wandering while simultaneously categorizing behavior using trained observers; the best of the four devices accounted for about 69% of the variance in observer-defined wandering. D. L. Algase, E. R. Beattie, S. A. Leitsch, C. A. Beel-Bates, Am. J. of Alz. Dis. & Oth. Dem. 18, 85-92 (2003).
In 2006, Teicher et al. used actigraphy in psychomotor assessment to diagnose psychiatric disorders including motor retardation, hyperactivity, catatonia, and early morning awakening. Teicher, M. H., McGreenery, C. E., & Ohashi, K., Actigraph assessment of rest-activity disturbances in psychiatric disorders: Psychosomatic Medicine, Proceedings of the 18th World Congress on Psychosomatic Medicine (pp. 32-37), International Congress Series. Teicher et al. identified total activity level, presence of sleep, and disturbed sleep-wake or rest-activity cycles as defining features of different disorders. The method used accelerometers on the body to continuously sample and store limb and trunk movements; however, it did not provide vector information.
These devices and methods have limitations and do not provide subject location and vector data, which is necessary to understand the variability in the paths taken by wandering subjects. Therefore, an automated assessment of episodic movements is needed that includes vector and duration information comparable or exceeding those derivable from accelerometry and gait mats.